New house - help me understand CH/HW system

[garmcqui]

Hi all,

We've just bought a new house and got the keys last week. We've always lived in flats and so always had combi boilers, but now we have a mains pressure hot water system, with tank etc, and I don't understand it!

I've taken a few pics in the hope someone can help...

This is the cupboard with the tank etc in it...

Now onto the questions:

1. What are these tanks? Do I need to open the valves to top up the system to make sure the black needle stays in the green zone (on the far tank)?

2. What are the three devices I've marked with red dots in this photo?

3. And finally, do I just leave this thing on "Auto"?


Sorry for all the questions, I'm a complete novice with this type of system and I don't like not knowing how it works...

Thanks!

Gareth

 

[Newboy]

The two tanks shown in your first photo are expansion vessels - leave well alone.

The pressure gauge should be around 1 bar when the system is cold. If it drops below this then you may need to top up the heating circuit using the two black quarter turn valves on the filling loop (the braided silver hose connected to the pressure gauge) - don't over pressure the system - 1 bar is enough when the system has cooled down.

The three fittings in your photo are 2 no. zone valves (the silver boxes) and the cylinder thermostat - set to control the temperature of your hot water.

Leave the valve in your last photo in the auto position

 

[garmcqui]

Hi, and thanks for your reply...

I will leave the valves alone - seems to be sitting around 1.5bar when the system is cold - is this a problem?

What do the zone valves do exactly? Are these only used for hot water or for central heating too?

The thermostat - it seems to be connected to the electric water heater (which I've never used yet) wall switch - does this also control the temperature of the hot water when heated using the gas boiler? What is the best temperature to set this at?

Cheers

 

[garmcqui]

more questions -

at the minute we have programmed the hot water part of the system to come on at 5.30am and go off at 6.30am - this seems to provide enough hot water for both my wife and I to get hot showers and there's usually some left over for washing up etc in the evening.

Is this the best way to have the system set? I understand that if it was on for longer, the tank thermostat would turn the boiler off anyway...

Gareth

 

[Newboy]

Pressure is fine as it is.

Zone valves control flow from the boiler to either (or both) hot water or heating circuit.


The cylinder stat is controlling the temperature of the cylinder when the boiler is heating the water circuit - is closes the relevant valve when the cylinder reaches temperature. The immersion heater temperature is controlled by a thermostat within the immersion heater itself.

Temperature is your choice - hot enough to be useful but not hot enough to scald! (mine's at around 55C)

It's an unvented system - anybody working on it needs to have a G3 ticket, system is perfectly safe but don't let unqualified people work on it.

 

[Whitespirit66]

Hot water is recommended to be around 55/60 - not high enough to present a serious scalding risk, not low enough to allow the growth of legionella bacteria.

Not recommended to keep water overheated (70+), as this can encourage scale deposits in hw cylinder if in a hard water area.